Silicon single crystal substrates for use in semiconductor substrates are manufactured by performing processes including slicing, chamfering, lapping, etching, and mirror-polishing on silicon single crystal ingots pulled, for example, by the CZ (Czochralski) method.
A method for growing a silicon epitaxial layer by vapor phase epitaxy is also used to improve crystal quality at a surface portion of the silicon single crystal substrate. In this method, the silicon epitaxial layer is grown by supplying silicon raw material to a main surface of the silicon single crystal substrate under a high temperature condition.
It is known that the method for manufacturing a silicon epitaxial wafer (hereinafter, also referred to as an epitaxial wafer alone) may produce surface irregularities according to conditions, thereby deteriorating device characteristics.
For example, Patent Document 1 proposes a method for preventing the surface irregularities, in which crystallographic step density of a main surface of the silicon single crystal substrate on which the epitaxial layer is grown is controlled to be equal to or less than approximately 1010 number/cm2.
Patent Document 2 proposes a method of regulating the angle range of a crystal axis with respect to the surface of the silicon single crystal substrate to reduce irregularities referred to as “haze”.
Patent Document 3 proposes a method of growing a silicon epitaxial layer on a silicon single crystal substrate having defects referred to as COP (Crystal Originated Particle) while regulating the angle range of a crystal axis with respect to the surface of the silicon single crystal substrate to prevent irregularities referred to as “teardrop”.
In the vapor phase epitaxy method for growing the silicon epitaxial layer on the silicon single crystal substrate, there is a problem in that doping with dopant at high concentrations in the epitaxial layer growth causes formation of stripe-shaped steps on the epitaxial layer surface, thereby deteriorating its surface shape.